Buckling resistance of hot‐finished CHS beam‐columns using FE modelling and machine learning

The use of circular hollow sections (CHS) has increased in recent years owing to its excellent mechanical behaviour including axial compression and torsional resistance as well as its aesthetic appearance. They are popular in a wide range of structural members including beams, columns, trusses and arches. The behaviour of hot-finished CHS beam-columns made from normal and high strength steel is the main focus of this paper. A particular attention is given to predict the ultimate buckling resistance of CHS beam-columns using the recent advancement of the artificial neural network (ANN). FE models were established and validated to generate an extensive parametric study. The ANN model is trained and validated using a total of 3439 data points collected from the generated FE models and experimental tests available in the literature. A comprehensive comparative analysis with the design rules in Eurocode 3 is conducted to evaluate the performance of the developed ANN model. It is shown that the proposed ANN based design formula provides a reliable means for predicting the buckling resistance of the CHS beam-columns. This formula can be easily implemented in any programming software, providing an excellent basis for engineers and designers to predict the buckling resistance resistance of the CHS beam-columns with a straightforward procedure in an efficient and sustainable manner with least computational time

Effects of the cooling system parameters on heat transfer and performance of the PAFC stack during transient operation

An experimental investigation for the effects of transient operation of a phosphoric acid fuel-cell stack on heat transfer and temperature distribution in the electrodes has been conducted. The proposed work utilized the experimental setup with modifications, which was designed and constructed under NASA Contract No. NCC-3-17(5). The experimental results obtained from this investigation and the mathematical model obtained under NASA Contract No. NCC3-17(4) after modifications, were utilized to develop mathematical models for transient heat transfer coefficient and temperature distribution in the electrode and to evaluate the performance of the cooling - system under unsteady state conditions. The empirical formulas developed were then implemented to modifying the developed computer code. Two incompressible coolants were used to study experimentally the effect of the thermophysical properties of the cool-ants on the transient heat transfer coefficient and the thermal contact resistance during start-up and shut-down processes. Coolant mass flow rates were verified from 16 to 88.2 Kg/hr during the transient process when the electrical power supply was gradually increased or decreased in the range (O to 3000 W/sq m). The effect of the thermal contact resistance with a range of stack pressure from O to 3500 KPa was studied

Microbiological evaluation of shelflife indices of fermented African locust bean cake stored under different preservative treatments

This study was carried out on the preservation of fermented Parkia biglobosa Seeds sourced from Local Producers and laboratory produced. The local and fermented laboratory controlled samples were treated with 0.5ml of freshly prepared ginger extract. Another set of control was left untreated. The samples were stored at ambient temperature for 30 and 120 days. Contaminant isolates were identified from locally produced, laboratory treated and untreated (Control) using standard procedure. The analysis consisted of Aerobic and Anaerobic mesophilic count, Staphylococcus count and fungal count, detection of E. coli, S. aureus, Salmonella sp, Mucor sp and Rhizopus sp. The proximate analysis and organoleptic assessment of the purchased, Laboratory treated and laboratory untreated (control) were carried out using standard procedure at 30 and 120 days. Isolated and characterized bacterial isolates at 30 and 120 days in the treated and control locust bean cake were E.coli only isolated in Kwanar yandaddawa, Staphylococcus aureus was isolated in all the purchased Locust bean cake, Salmonella sp was not detected and a predominant fungalspecies were Mucor and Rhizopus. There was log reduction between 30 and 120 days  reated locust bean cake; the Control shows Log increase. The mean proximate composition percentage differences between 30 and 120 days shows nutritional quality of treated locust bean cake. Organoleptically, the judges rejected control daddawa as a result of what the panelist termed as “unpalatable taste and partially pleasant aroma” due to off flavor. The growing interest in use of natural products of plant origin therefore gives Ginger extract an advantage in developing a practical approach for the preservation of African locust bean cake.Keywords: African locust bean cake, preservatives, log reduction, nutritional quality, shelflife

Efisiensi Daya Tahan Baterai pada Sistem Keamanan Ksatrian dengan Pir Menggunakan Kontrol Pid

Sensor PIR adalah sensor yang mendeteksi adanya pancaran sinar inframerah yang dikeluarkan oleh manusia. Sensor PIR ini bersifat pasif, jadi sensor PIR ini tidak memancarkan sinar inframerah tetapi menangkap pancaran sinar inframerah yang dikeluarkan oleh benda-benda disekelilingnya. Pada penelitian kali ini sensor PIR digunakan untuk mendeteksi adanya seseorang yang ingin menyusup masuk dalam suatu asrama ksatrian TNI AD. Daya yang dikonsumsi oleh sensor PIR diatur seefisien mungkin sehingga daya tahan baterai dapat digunakan secara maksimal. Daya yang dikonsumsi sensor PIR dikontrol menggunakan kontrol PID dengan menaikkan dan menurunkan tegangan sesuai dengan karakteristik sensor PIR yang digunakan

Penilaian Lesan Dada Tidak Bernilai Pada Ttc Menggunakan Morfologi Citra Digital

Sistem Latihan menembak merupakan salah satu hal terpenting dalam dunia militer. Pelaksanaan latihan tersebut terdapat beberapa materi yang diterapkan sesuai dengan kebutuhan TNI AD.. Setiap prajurit TNI AD diwajibkan untuk memperoleh sertifikat tersebut. Salah satu materi latihan menembak dalam TNI AD yaitu Tembak Tempur Cepat. Tembak tempur cepat adalah latihan menembak dengan berjalan yang diperumpamakan bertemu dengan musuh secaa tiba-tiba. Lesan yang digunakan adalah lesan dada tidak bernilai yang bergerak secara tiba-tiba. Dimana sistem pelaksanaannya masih manual yaitu masih menggunakan tenaga manusia baik untuk menggerkan lesan maupun sistem penilaiannya. Sistem penilaian yang masih manual membuat sistem penilaian tidak obyektif. Sistem penilaian masih manual yaitu dengan melihat secara mata visual. Dengan memanfaatkan sinar matahari maka sistem penilaian dapat menggunakan kamera dengan menggunakan metode pengolahan citra digital. Pengolahan citra digital adalah suatu metode yang digunakan untuk membedakan warna. Dengan memanfaatkan sinar matahari maka pengolahan citra sangat cocok digunakan untuk membedakan warna antara lesan yang tidak berlubang dan lesan yang berlubang karena hasil tembakan sehingga nilai tembakan petembak dapat dibaca oleh pengolahan citr

Bond behaviour of austenitic stainless steel reinforced concrete

Stainless steel reinforced concrete has seen a large increase in usage in recent years, in response to the ever-increasing demands for structures and infrastructure to be more durable, efficient and sustainable. Currently, existing design standards advise using the same design rules for stainless steel reinforced concrete as traditional carbon steel reinforced concrete, owing to a lack of alternative information. However, this is not based on test or performance data. As such, there is a real need to develop a full and fundamental understanding of the bond behaviour of stainless steel reinforced concrete, to achieve more sustainable and reliable design methods for reinforced concrete structures. This paper investigates the bond behavior of stainless steel reinforced concrete and compares the performance to traditional carbon steel reinforced concrete, through experimental testing and analysis. It also compares the results to existing design rules in terms of bond strength, anchorage length and lap length. It is shown that stainless steel rebar generally develops lower bond strength with the surrounding concrete compared with equivalent carbon steel reinforcement. Moreover, it is shown that existing design codes are very conservative and generally underestimate the actual bond strength by a significant margin. Therefore, following detailed analysis, it is concluded that current design rules can be safely applied for stainless steel rebar, although more accurate and efficient methods can be achieved. Hence, new design parameters are proposed reflecting the bond behaviour of stainless steel rebar, so that more efficient designs can be achieved. Moreover, a summary of recommendations for the codes of practice is provided

INCORPORATION OF A TWO-FLUX MODEL FOR RADIATIVE HEAT TRANSFER IN A COMPREHENSIVE FLUIDIZED BED SIMULATOR PART I: PRELIMINARY THEORETICAL INVESTIGATIONS

Over the last two decades, a comprehensive mathematical model and its corresponding computational program, aimed to simulate steady-state operations of bubbling fluidized bed equipments, has been continuously improved and tested. Despite its success, the simulator has employed a simple approach for radiative heat transfers. In cases of high temperatures, thermal radiation becomes an important energy transfer mode and the original model could lead to deviations above acceptable levels. The purpose of the present work was to improve the model for thermal radiation heat transfer between all solid particles in the bed section by applying a two-flux method to a non-homogeneous polydispersed particulate media in radiative equilibrium. Gases in the emulsion and in the bubbles were assumed transparent to thermal radiation. This first part of the paper presents and discusses the basic structure of the former mathematical model and of the new one

New solutions of relativistic wave equations in magnetic fields and longitudinal fields

We demonstrate how one can describe explicitly the present arbitrariness in solutions of relativistic wave equations in external electromagnetic fields of special form. This arbitrariness is connected to the existence of a transformation, which reduces effectively the number of variables in the initial equations. Then we use the corresponding representations to construct new sets of exact solutions, which may have a physical interest. Namely, we present new sets of stationary and nonstationary solutions in magnetic field and in some superpositions of electric and magnetic fields.Comment: 25 pages, LaTex fil